JPH0360384A - Micropump - Google Patents

Abstract

PURPOSE:To enable large output realization without needing a special amplitude magnifying mechanism by equipping an oscillator, which oscillates in the resonant conditions being given approximately elliptic oscillation, and a pump room capable of varying the content volume by oscillation of this oscillator. CONSTITUTION:For an oscillator used for a micropump, an ultrasonic oscillator 16 is used. In this ultrasonic oscillator 16, the first piezoelectric Substance 22 for giving curved oscillations to an elastic body 21 is mounted on the top of the elastic body 21 in rectangular plate shape, and in the elastic body 21, the second piezoelectric substances 23a and 23b for giving vertical oscillation to the elastic body 21 are mounted at the side faces which cross the mounting face nearly at right angles. Moreover, for a pump room, the content volume can be changed by the oscillation of the oscillator 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pump, and particularly to a micropump capable of feeding a very small amount.

[Prior Art] Conventionally, various pumps using piezoelectric actuators have been proposed because they have the advantage that they can be driven directly and do not require a driving force conversion mechanism.

However, since the piezoelectric actuator alone has a very small displacement of 300 [pm/V] per unit voltage, it requires some kind of mechanism for enlarging the displacement. Therefore, pumps have been devised that use bimorph piezoelectric bodies with large displacements, laminated piezoelectric bodies, and expansion mechanisms that apply the lever principle. As a conventional example, an embodiment of a piezoelectric pump disclosed in Japanese Unexamined Patent Publication No. 62-276276 is shown in FIGS. 5 and 6.

The piezoelectric actuator 1 is integrally connected to levers 5 and 6 via displacement transmission members 3 and 4, and
is integrally connected to the fixing member 7 via hinges 8 and 9, and amplifies the amount of expansion/contraction displacement of the piezoelectric actuator element 1 based on the principle of leverage. Here, 10 and 11 are other displacement transmitting members, 12 is a pump body, 13 is a valve, and 4
is a nozzle.

[Problems to be Solved by the Invention] However, in the conventional pump described above, in the method using the lever principle, the larger the displacement magnification rate, the more complicated the expansion mechanism becomes, and the driving thrust becomes smaller. There were drawbacks.

Further, in the above-mentioned pump, a check valve is essential to prevent backflow of the driven object.

The expansion mechanism and check valve have quasi-static motion, and the frequency of the drive signal is limited to below the resonance frequency of each component (300 Hz in the prior art example), making it difficult to respond quickly. .

The present invention was made in order to solve the above-mentioned problems, and its purpose is to obtain a pump using a vibrator that can increase output without requiring a special amplitude expansion mechanism. There is.

Furthermore, it is possible to obtain unnecessary pumps with check valves, and tens of kilos.
Another objective is to obtain a high-speed response pump that can use Hz drive signals.

[Means for solving the problem] In order to achieve this object, the micropump of the present invention has the following features:
A vibrator that is excited with approximately elliptical vibration and vibrates in a resonant state;
The pump chamber is configured to include a pump chamber whose internal volume can be changed by the vibration of the vibrator.

Further, the vibrator has at least two drive sections, and is configured to be excited in the drive sections so that the phases of the substantially elliptical vibrations are opposite to each other.

[Function] In the micropump of the present invention having the above-mentioned configuration, the vibrator is excited in a resonant state by adjusting its shape and dimensions, so it generates approximately elliptical vibration with an amplitude several hundred times larger than that in a non-resonant state. I can do it.

The driven body within the pump chamber receives or is sent out a direct thrust by the approximately elliptical vibration.

At this time, since two or more driving parts formed on the vibrator alternately perform pump operations, the driven bodies are sent out one after another without backflow, and no check valve is required. Furthermore, if a thin tube made of a highly elastic material is used in the pump chamber,
Fine adjustment of discharge amount is possible.

For example, if a metal such as Ad or bronze is used as the vibrator elastic body, the resonance frequency, that is, the operating frequency, can be increased to several tens of kilohertz.
It is easy to achieve a value of z or more.

[Example 1] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

The ultrasonic vibrator used in the micropump of the present invention is, for example, the ultrasonic vibrator seen in the specification and drawings of Japanese Patent Application No. 1-46866.

1 and 2 show the ultrasonic transducer of this embodiment. In the ultrasonic transducer 16 of this embodiment, a first piezoelectric body 22 for exciting bending vibration in the elastic body 21 is attached to the upper surface of an elastic body 21 having a rectangular flat plate shape. In the elastic body 21, second piezoelectric bodies 23a and 23b for exciting longitudinal vibration in the elastic body 21 are attached to the side surfaces substantially orthogonal to the mounting surface.

The longitudinal center of the elastic body 21 is fixed by fixing bolts 24a and 24b for fixing the elastic body 21. The other ends of the fixing bolts 24a and 24b are
It is fixed to bases 25a and 25b.

An electrode 26 is provided on the upper surface of the first piezoelectric body 22 . Further, electrodes 27a and 27b are installed on the upper surfaces of the second piezoelectric bodies 23a and 23b. Further, the elastic body 21 itself also serves as a ground electrode, and the elastic body is connected to the bases 25a and 25 through the fixing bolts 24a and 24b.
It is grounded to 5b.

Further, the elastic body 21 bends in a secondary mode at both free ends at a predetermined frequency f in the thickness direction, and longitudinally vibrates in a primary mode at both free ends in the length direction at the same frequency f. The shape and dimensions have been adjusted.

Generally, the resonant frequency of longitudinal vibration propagating in an elastic body depends on the length of the elastic body. Further, the resonance frequency of bending vibration in the thickness direction of the elastic body depends on the length and thickness. Therefore, since it is easy to design the elastic body 21 as described above, the details thereof will be omitted.

The operation of the ultrasonic transducer 16 configured as above will be explained below.

First, when an alternating voltage of the predetermined frequency f is applied to the first piezoelectric body 22 to cause it to vibrate, the elastic body 21 resonates in a secondary mode of bending vibration.

Next, when an alternating voltage of the frequency f is applied to the second piezoelectric bodies 23a and 23b to cause them to vibrate, the elastic body 21 resonates in the first mode of longitudinal vibration. In other words, the fixing bolt 24
The positions fixed by a and 24b are nodes of each standing wave.

At this time, by adjusting the amplitude and phase of the voltages applied to the first piezoelectric body 22 and the second piezoelectric bodies 23a and 23b, it is possible to generate approximately elliptical vibration of an arbitrary shape in the elastic body 21. .

The operation of a micropump that suitably utilizes the above-mentioned ultrasonic vibrator will be explained based on FIG. 3. In FIG. 3, each member given the same reference numeral as in FIGS. 1 and 2 means the same as each component described in detail above.

The micropump 31 is made of a thin rubber tube 32 that is a highly elastic material.
The ultrasonic transducer 16 is brought into contact with the elastic body 21 of the ultrasonic transducer 11, and drive parts 33a and 33b are formed on the same surface at both ends. In these two driving parts 33a and 33bl, the phases of the substantially elliptical vibrations are exactly opposite to each other.

In the micropump 31 configured as described above, when an alternating current voltage of a predetermined frequency f is applied to the piezoelectric bodies 22 and 23 of the ultrasonic vibrator 16, the ultrasonic vibrator 16 generates a large-amplitude approximately elliptical vibration. It is excited, and its amplitude is about several micrometers to several tens of micrometers.

Due to the elliptical vibration, the driving section 32a operates to crush the thin tube 32, as shown in FIG. 3(a). Due to the compressive force, the fluid 34 in the thin tube 32 is moved to the direction indicated by the arrow C in the figure.
Receives driving force in the direction of. The drive section 32a is a thin tube 32
When separated, the driving part 32b whose vibration phase is in the opposite direction compresses the thin tube 32 as shown in FIG. In this way, the fluid 34 receives the driving force substantially continuously from the driving parts 32a and 32b, so that it is discharged without backflowing. Therefore, pump operation is possible without using a check valve.

Although the above embodiments have been described using an example of a vibrator that excites a standing wave, the present invention is not limited to this, and various types of vibrators such as a vibrator that excites a traveling wave can be used.

Further, in the above embodiment, the vibration frequency of the vibrator is in the ultrasonic range, but it is not limited to this, and it is also possible to use a low frequency of about several Hz to several hundred Hz.

Furthermore, although an example in which the elastic body and piezoelectric body of the ultrasonic transducer are rectangular flat plates has been described, it is possible to take various shapes such as a disk shape, nine annular shapes, one cylindrical shape, a rod shape, and a rectangular shape.

The structure of a pipette 41 that suitably utilizes the above-mentioned micropump 31 will be explained based on FIG. 4.

In this figure, each member given the same reference numeral as in FIGS. 1 to 3 means the same as each component described in detail above.

In the pipette 41, a tank 43 for storing the fluid 34 is formed in a yoke 42, and a first channel 44 for connecting the tank 43 and the micropump 31 is arranged. Furthermore, in the discharge direction of the micro pump 31, a second
A flow path 45 is arranged. On the other hand, in order to drive the micro pump 31, a battery 46 and a control circuit 47 are connected. The battery 46 is extremely miniaturized by using a vapor battery. Also, 4
8 is a lid of the tank 43.

In the pipette 41 configured as described above, the amount of discharge per micropump 310 is very small, so accurate control of the amount of discharge is possible.

In addition, various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] As is clear from the above detailed description, the present invention provides a pump that uses a vibrator and is capable of increasing output without requiring a special amplitude expansion mechanism. You can get it. Furthermore, a pump that does not require a check valve can be obtained.

[Brief explanation of drawings]

1 to 3 show embodiments embodying the present invention. FIG. 1 is a top view showing the top surface of the ultrasonic vibrator used in the present invention, and FIG. FIG. 3 is a schematic diagram showing the operation of a micropump to which the present invention is applied, FIG. 4 is a sectional view of a pipette to which the present invention is applied, and FIG. 5 is a schematic diagram of a conventional piezoelectric pump. FIG. 6 is a schematic diagram of a conventional piezoelectric pump. In the figure, 16 is an ultrasonic transducer, 31 is a micro pump, and 3
2 is a thin tube, and 33 is a driving section.

Claims (1)

[Claims] 1. A micropump characterized by comprising a vibrator that is excited with approximately elliptical vibration and vibrates in a resonant state, and a pump chamber whose internal volume can be changed by the vibration of the vibrator. 2. The micropump according to claim 1, wherein the vibrator has at least two drive parts, and is excited in the drive parts so that the phases of the substantially elliptical vibrations are opposite to each other. micro pump. 3. The micropump according to claim 1 or 2, wherein a thin tube made of a highly elastic material is used as the pump chamber.